How Do I Compare Two Text Files For Differences?

Comparing two text files for differences can be efficiently achieved using various methods. This comprehensive guide from compare.edu.vn explores several effective strategies, including command-line tools, graphical user interfaces, and online comparison tools, ensuring you can choose the best approach for your needs. Delve into file comparison and text analysis techniques to pinpoint changes, additions, and deletions between files.

1. What Are the Common Methods to Compare Two Text Files?

There are several common methods to compare two text files, including command-line tools, graphical user interfaces (GUIs), and online comparison tools. Each method offers different features and benefits, allowing you to choose the one that best suits your needs and technical expertise. Let’s explore these options in detail.

1.1 Using Command-Line Tools

Command-line tools are powerful utilities that allow you to compare text files directly from the terminal or command prompt. These tools are often preferred by developers and system administrators due to their efficiency and flexibility. Two of the most popular command-line tools for file comparison are diff and cmp.

1.1.1 The diff Command

The diff command is a standard Unix utility that compares two files and outputs the differences between them. It is available on most Unix-like operating systems, including Linux and macOS, and can also be used on Windows via the Cygwin or Git Bash environments.

Syntax:

diff [options] file1 file2

Example:

To compare two files named file1.txt and file2.txt, you would use the following command:

diff file1.txt file2.txt

Output Interpretation:

The diff command provides output in a specific format that indicates the differences between the files. The output consists of a series of “hunks,” each representing a set of changes. Here’s how to interpret the output:

• Lines starting with < indicate lines that are present in the first file but not in the second file.
• Lines starting with > indicate lines that are present in the second file but not in the first file.
• Lines starting with - are separators between the changes.
• The change indicators (e.g., 2a3, 4d3, 5c5) describe the type and location of the changes.

For example, consider the following output:

2a3
> This is a new line in file2.txt
4d3
< This line is only in file1.txt
5c5
< This line has been changed in file1.txt
---
> This line has been changed in file2.txt

In this output:

• 2a3 means “add after line 2 in file1.txt, the following line from file2.txt.”
• 4d3 means “delete line 4 in file1.txt.”
• 5c5 means “change line 5 in file1.txt`` to the following line infile2.txt`.”

Common Options:

• -u or --unified: This option generates a “unified diff,” which provides more context by including several lines before and after each change. This format is commonly used for creating patches.
• -y or --side-by-side: This option displays the two files side by side, highlighting the differences.
• -i or --ignore-case: This option ignores case differences when comparing the files.
• -w or --ignore-all-space: This option ignores whitespace differences.
• -B or --ignore-blank-lines: This option ignores changes that involve only blank lines.

Example with Unified Diff:

diff -u file1.txt file2.txt

This command produces a unified diff, which is easier to read and use for patching. The output will look something like this:

--- file1.txt   2024-07-26 10:00:00.000000000 -0700
+++ file2.txt   2024-07-26 10:05:00.000000000 -0700
@@ -1,5 +1,6 @@
 This is the first line.
 This is the second line.
+This is a new line in file2.txt
 This line is only in file1.txt
 This is the fourth line.
-This line has been changed in file1.txt
+This line has been changed in file2.txt

In this unified diff:

• Lines starting with --- indicate the original file (file1.txt).
• Lines starting with +++ indicate the new file (file2.txt).
• Lines starting with + indicate lines added in file2.txt.
• Lines starting with - indicate lines removed from file1.txt.
• Lines starting with a space indicate lines that are the same in both files.

1.1.2 The cmp Command

The cmp command is another command-line tool used to compare two files. Unlike diff, which identifies the specific differences, cmp simply indicates whether the files are identical or, if not, the first byte where they differ.

Syntax:

cmp [options] file1 file2

Example:

To compare two files named file1.txt and file2.txt, you would use the following command:

cmp file1.txt file2.txt

Output Interpretation:

• If the files are identical, cmp will not produce any output.
• If the files are different, cmp will output the byte and line number where the first difference occurs.

For example, if file1.txt and file2.txt differ at byte 42 on line 5, the output might look like this:

file1.txt file2.txt differ: byte 42, line 5

Common Options:

• -l or --verbose: This option outputs the byte number (decimal) and the differing byte values (octal) for each difference.
• -s or --silent or --quiet: This option suppresses all normal output. It is useful for scripting when you only need to know the exit status (0 for identical, 1 for different).

Example with Verbose Output:

cmp -l file1.txt file2.txt

This command provides a detailed comparison, showing each differing byte:

42 101 102
43 102 103

In this verbose output, the first number is the byte number, and the following two numbers are the octal values of the differing bytes in each file.

1.2 Using Graphical User Interfaces (GUIs)

Graphical user interfaces (GUIs) offer a more visual and user-friendly way to compare text files. These tools typically display the files side by side, highlighting the differences with colors and allowing you to easily navigate and review the changes.

1.2.1 Dedicated Diff Tools

Several dedicated diff tools are available for various operating systems. These tools are specifically designed for file comparison and offer advanced features such as:

• Syntax highlighting
• Merge capabilities
• Directory comparison
• Support for various file formats

Examples of Popular GUI Diff Tools:

• Meld (Linux): Meld is a visual diff and merge tool designed for developers. It allows you to compare files, directories, and version-controlled projects. Meld provides a clear and intuitive interface for reviewing and merging changes.
• Beyond Compare (Windows, macOS, Linux): Beyond Compare is a powerful and versatile diff tool that supports file and folder comparisons, FTP sites, and cloud storage. It offers advanced features like syntax highlighting, session management, and three-way merge.
• Araxis Merge (Windows, macOS): Araxis Merge is a professional-grade diff and merge tool that provides advanced features for comparing and synchronizing files and folders. It supports three-way visual file comparison and automatic merging.
• KDiff3 (Windows, macOS, Linux): KDiff3 is a free and open-source diff and merge tool that supports comparing two or three files or directories. It provides automatic merge capabilities and a user-friendly interface.

Using Meld to Compare Files:

1. Installation: Install Meld using your distribution’s package manager. For example, on Debian-based systems:

   sudo apt-get install meld

2. Running Meld: Open Meld from your application menu or by typing meld in the terminal.

3. Comparing Files: Select the “File comparison” option and choose the two files you want to compare.

4. Reviewing Differences: Meld displays the files side by side, highlighting the differences with colors. You can navigate through the changes using the arrow buttons and merge changes by clicking on the corresponding blocks.

1.2.2 Text Editors with Diff Features

Many advanced text editors come with built-in diff features that allow you to compare files directly within the editor. This can be very convenient if you are already using a particular text editor for your development or writing tasks.

Examples of Text Editors with Diff Features:

• Visual Studio Code (Windows, macOS, Linux): VS Code is a popular and versatile text editor that supports a wide range of programming languages and provides excellent diff capabilities. You can compare files by right-clicking on a file in the Explorer pane and selecting “Select for Compare,” then right-clicking on another file and selecting “Compare with Selected.”
• Sublime Text (Windows, macOS, Linux): Sublime Text is a sophisticated text editor with a clean and distraction-free interface. It offers a file comparison feature that highlights the differences between files in a clear and concise manner.
• Notepad++ (Windows): Notepad++ is a free and open-source text editor for Windows that includes a plugin called “Compare Plugin.” This plugin allows you to compare two files side by side, highlighting the differences with colors.

Using Visual Studio Code to Compare Files:

1. Open Files: Open the two files you want to compare in VS Code.
2. Select for Compare: Right-click on one of the files in the Explorer pane and select “Select for Compare.”
3. Compare with Selected: Right-click on the other file and select “Compare with Selected.”
4. Reviewing Differences: VS Code displays the files side by side, highlighting the differences with colors. You can navigate through the changes using the arrow buttons and make edits directly in the editor.

1.3 Using Online Comparison Tools

Online comparison tools provide a convenient way to compare text files without the need to install any software. These tools are typically web-based and allow you to upload or paste the content of the files you want to compare.

1.3.1 Popular Online Diff Tools

Several online diff tools are available, offering various features and options for comparing text files.

Examples of Popular Online Diff Tools:

• Diffchecker: Diffchecker is a simple and easy-to-use online diff tool that allows you to compare text files by pasting or uploading them. It highlights the differences with colors and provides a clear and concise output.
• Online Diff Tool: Online Diff Tool is another popular online diff tool that supports various comparison options, such as ignoring whitespace and case differences. It provides a side-by-side comparison and allows you to download the diff output.
• Code Beautify Diff Viewer: Code Beautify Diff Viewer is a free online tool for comparing text files and code snippets. It supports syntax highlighting and provides a visual representation of the differences between the files.
• Text Compare!: Text Compare! is an online tool that lets you compare texts. It provides a simple interface and highlights the differences using color-coding.

Using Diffchecker to Compare Files:

1. Access Diffchecker: Open Diffchecker in your web browser.
2. Input Files: Paste the content of the two files you want to compare into the text boxes.
3. Compare: Click the “Find Difference” button.
4. Reviewing Differences: Diffchecker displays the files side by side, highlighting the differences with colors. You can scroll through the files and review the changes.

2. How Can I Choose the Right Tool for My Needs?

Choosing the right tool depends on your specific needs, technical expertise, and the complexity of the comparison task. Here’s a guide to help you make the best choice:

2.1 Consider the Complexity of the Task

• Simple Comparisons: For quick, simple comparisons, online tools like Diffchecker or basic command-line tools like cmp may suffice. These tools are easy to use and provide a straightforward way to identify differences.
• Complex Comparisons: For more complex comparisons involving large files, multiple changes, or the need to merge differences, dedicated GUI diff tools like Beyond Compare or Araxis Merge are more suitable. These tools offer advanced features and a visual interface that simplifies the comparison process.

2.2 Evaluate Your Technical Expertise

• Beginners: If you are new to file comparison, GUI tools are generally easier to use. They provide a visual interface that allows you to see the differences between files without having to understand complex command-line syntax.
• Experienced Users: If you are comfortable with the command line, tools like diff and cmp can be very efficient. They allow you to quickly compare files and integrate the comparison process into scripts and automated workflows.

2.3 Assess the Need for Additional Features

• Syntax Highlighting: If you are comparing code files, syntax highlighting can make it easier to identify changes. Look for tools that support syntax highlighting for your programming languages.
• Merge Capabilities: If you need to merge the differences between files, choose a tool that offers merge capabilities. This will allow you to combine the changes from both files into a single file.
• Directory Comparison: If you need to compare entire directories of files, choose a tool that supports directory comparison. This will allow you to quickly identify the files that have changed between the directories.

2.4 Consider the Operating System

• Windows: For Windows users, Notepad++ with the Compare Plugin, Beyond Compare, and Araxis Merge are excellent choices.
• macOS: For macOS users, Araxis Merge, Beyond Compare, and KDiff3 are popular options.
• Linux: For Linux users, Meld, KDiff3, and command-line tools like diff and cmp are commonly used.

2.5 Review the Cost

• Free Tools: Many free and open-source diff tools are available, such as Meld, KDiff3, and Notepad++ with the Compare Plugin. These tools offer a wide range of features and are suitable for many comparison tasks.
• Commercial Tools: Commercial diff tools like Beyond Compare and Araxis Merge offer advanced features and support but come at a cost. Consider whether the additional features are worth the investment for your specific needs.

3. What Are the Key Features to Look for in a Text Comparison Tool?

When selecting a text comparison tool, several key features can significantly enhance your experience and efficiency. These include syntax highlighting, ignore options, side-by-side view, merge capabilities, directory comparison, and support for various file formats.

3.1 Syntax Highlighting

Syntax highlighting is a feature that displays code and markup languages in different colors and fonts according to the syntax rules. This makes it easier to read and understand the code, and it can also help you quickly identify changes and errors.

• Benefits:

  • Improved readability of code files.
  • Easier identification of syntax errors.
  • Quick detection of changes in code structure.

• Example:
  A diff tool with syntax highlighting can display keywords, variables, and comments in different colors, making it easier to see the changes in a code file.

3.2 Ignore Options

Ignore options allow you to exclude certain types of differences from the comparison, such as whitespace, case differences, and comments. This can be useful when you want to focus on the significant changes in the files.

• Benefits:

  • Reduced clutter in the comparison output.
  • Focus on meaningful changes.
  • Customization of the comparison process.

• Example:
  You can use the “ignore whitespace” option to compare two code files without being distracted by differences in indentation or line breaks.

3.3 Side-by-Side View

A side-by-side view displays the two files being compared next to each other, highlighting the differences with colors. This makes it easy to see the changes in context and to compare the files line by line.

• Benefits:

  • Clear visual representation of the differences.
  • Easy comparison of corresponding lines.
  • Improved understanding of the changes.

• Example:
  A side-by-side view can show you the exact lines that have been added, deleted, or modified in each file.

3.4 Merge Capabilities

Merge capabilities allow you to combine the changes from two files into a single file. This can be useful when you need to integrate changes from different versions of a file or when you are collaborating with others on a project.

• Benefits:

  • Easy integration of changes.
  • Resolution of conflicts.
  • Streamlined collaboration.

• Example:
  You can use the merge feature to combine the changes made by two developers in different branches of a Git repository.

3.5 Directory Comparison

Directory comparison allows you to compare entire directories of files, identifying the files that have been added, deleted, or modified. This can be useful when you need to synchronize files between two directories or when you are managing a large project with many files.

• Benefits:

  • Quick identification of changed files.
  • Synchronization of directories.
  • Efficient management of large projects.

• Example:
  You can use directory comparison to synchronize the files between your local development environment and a remote server.

3.6 Support for Various File Formats

Support for various file formats ensures that the diff tool can handle different types of files, such as code files, text files, configuration files, and more. This can be useful when you are working with a variety of file types in your projects.

• Benefits:

  • Versatile comparison capabilities.
  • Support for different types of files.
  • Consistent comparison experience.

• Example:
  A diff tool that supports multiple file formats can compare code files in different programming languages, such as Python, Java, and JavaScript.

4. How to Compare Text Files Using the diff Command in Linux?

The diff command is a powerful utility in Linux for comparing text files. It highlights the differences between two files, making it an essential tool for developers and system administrators. This section provides a detailed guide on how to use the diff command effectively.

4.1 Basic Usage of the diff Command

The basic syntax for using the diff command is as follows:

diff file1 file2

This command compares file1 and file2 and outputs the differences in a format that indicates the changes needed to make the files identical.

Example:

Suppose you have two files, file1.txt and file2.txt, with the following content:

file1.txt

This is the first line.
This is the second line.
This line is only in file1.txt
This is the fourth line.
This line has been changed in file1.txt

file2.txt

This is the first line.
This is the second line.
This is a new line in file2.txt
This is the fourth line.
This line has been changed in file2.txt

To compare these files, run the following command:

diff file1.txt file2.txt

The output will be:

2a3
> This is a new line in file2.txt
4d4
< This line is only in file1.txt
5c5
< This line has been changed in file1.txt
---
> This line has been changed in file2.txt

4.2 Understanding the diff Output

The output of the diff command can be interpreted as follows:

• 2a3: This means “add after line 2 in file1.txt, the following line from file2.txt.”
• >: Indicates the line that needs to be added.
• 4d4: This means “delete line 4 in file1.txt.”
• <: Indicates the line that needs to be deleted.
• 5c5: This means “change line 5 in file1.txt to the following line in file2.txt.”
• ---: Separator between the lines to be changed.

4.3 Using the Unified Diff Format (-u option)

The -u option generates a unified diff, which is more readable and commonly used for creating patches. It includes context lines around the changes, making it easier to understand the differences.

Syntax:

diff -u file1 file2

Example:

Using the same files as before, run the following command:

diff -u file1.txt file2.txt

The output will be:

--- file1.txt   2024-07-26 10:00:00.000000000 -0700
+++ file2.txt   2024-07-26 10:05:00.000000000 -0700
@@ -1,5 +1,6 @@
 This is the first line.
 This is the second line.
+This is a new line in file2.txt
 This line is only in file1.txt
 This is the fourth line.
-This line has been changed in file1.txt
+This line has been changed in file2.txt

Interpreting the Unified Diff Output:

• --- file1.txt: Indicates the original file.
• +++ file2.txt: Indicates the new file.
• @@ -1,5 +1,6 @@: Indicates the range of lines being compared. In this case, it starts at line 1 in file1.txt and file2.txt, spans 5 lines in file1.txt, and 6 lines in file2.txt.
• +: Indicates a line added in file2.txt.
• -: Indicates a line removed from file1.txt.
• ` `: Indicates a line that is the same in both files.

4.4 Ignoring Whitespace (-w option)

The -w option ignores whitespace differences between the files. This is useful when you want to focus on the content changes and ignore differences in indentation or line breaks.

Syntax:

diff -w file1 file2

Example:

Suppose you have two files with different whitespace:

file1.txt

This is the first line.
  This is the second line.

file2.txt

This is the first line.
This is the second line.

Run the following command:

diff -w file1.txt file2.txt

The output will be empty because the only difference is whitespace.

4.5 Ignoring Case (-i option)

The -i option ignores case differences between the files. This is useful when you want to compare files regardless of whether the text is in upper or lower case.

Syntax:

diff -i file1 file2

Example:

Suppose you have two files with different casing:

file1.txt

This is the first line.
This is the SECOND line.

file2.txt

This is the first line.
This is the second line.

Run the following command:

diff -i file1.txt file2.txt

The output will be:

2c2
< This is the SECOND line.
---
> This is the second line.

4.6 Displaying Files Side by Side (-y option)

The -y option displays the files side by side, highlighting the differences. This can be useful for visually comparing the files and seeing the changes in context.

Syntax:

diff -y file1 file2

Example:

Using the same files as in the basic example, run the following command:

diff -y file1.txt file2.txt

The output will be:

This is the first line.                This is the first line.
This is the second line.               This is the second line.
This line is only in file1.txt          | This is a new line in file2.txt
This is the fourth line.               This is the fourth line.
This line has been changed in file1.txt  | This line has been changed in file2.txt

The | symbol indicates lines that are different.

4.7 Ignoring Blank Lines (-B option)

The -B option ignores changes that involve only blank lines. This is useful when you want to focus on the content changes and ignore differences in the number of blank lines.

Syntax:

diff -B file1 file2

4.8 Comparing Directories

The diff command can also compare directories. When used with the -r option, it recursively compares files in two directories and reports the differences.

Syntax:

diff -r dir1 dir2

Example:

Suppose you have two directories, dir1 and dir2, with different files and content. Run the following command:

diff -r dir1 dir2

The output will show the differences between the files in the two directories.

5. How Can I Use Online Tools to Compare Large Text Files?

Online tools offer a convenient way to compare text files without installing software. However, large text files can pose challenges due to size limitations and performance issues. Here’s how to effectively use online tools for comparing large text files.

5.1 Understanding the Limitations of Online Tools

Before attempting to compare large text files with online tools, it’s important to understand their limitations:

• File Size Limits: Many online tools impose restrictions on the size of the files you can upload or paste. This is to prevent server overload and ensure fair usage.
• Performance: Comparing large files can be resource-intensive, leading to slow processing times and potential timeouts.
• Privacy: Uploading sensitive data to online tools may raise privacy concerns. Ensure the tool you use has a strong privacy policy and encryption measures.

5.2 Choosing the Right Online Tool

Select an online tool that is designed to handle large files or offers features that mitigate the limitations mentioned above.

Recommended Online Tools:

• Diffchecker: Diffchecker is a popular online tool that can handle relatively large files. It offers a clean interface and highlights differences effectively.
• Online Diff Tool: This tool supports various options for ignoring whitespace and case differences, which can help reduce the comparison load.
• Code Beautify Diff Viewer: Code Beautify offers a diff viewer that supports syntax highlighting and provides a visual representation of the differences, making it easier to review changes in code files.

5.3 Best Practices for Comparing Large Files Online

To optimize the comparison process for large files, consider the following best practices:

• Reduce File Size: If possible, try to reduce the file size by removing unnecessary content, such as comments, whitespace, or irrelevant data.
• Use Ignore Options: Utilize the ignore options provided by the online tool to exclude whitespace, case differences, and other non-essential changes. This can significantly reduce the processing time.
• Compare Sections: If the file is too large to compare at once, divide it into smaller sections and compare each section separately. This can help avoid file size limits and improve performance.
• Use Local Tools: If online tools consistently fail due to size limitations, consider using local tools like command-line diff or GUI-based diff tools, which are better equipped to handle large files.

5.4 Step-by-Step Guide Using Diffchecker

Here’s a step-by-step guide on how to compare large text files using Diffchecker:

1. Access Diffchecker: Open Diffchecker in your web browser.
2. Input Files: Paste the content of the two files you want to compare into the text boxes. For large files, ensure you are within the tool’s size limits.
3. Compare: Click the “Find Difference” button.
4. Reviewing Differences: Diffchecker displays the files side by side, highlighting the differences with colors. Scroll through the files and review the changes.

5.5 Alternative Approaches

If online tools are not suitable for your needs, consider these alternative approaches:

• Command-Line Tools: Use command-line tools like diff in Linux or similar tools in other operating systems. These tools are designed to handle large files efficiently.
• GUI-Based Diff Tools: Install a GUI-based diff tool like Beyond Compare or Araxis Merge, which can handle large files and provide advanced comparison features.
• Code Editors: Some code editors, like Visual Studio Code, have built-in diff capabilities that can handle large files effectively.

6. How to Automate Text File Comparison with Scripting?

Automating text file comparison with scripting can save significant time and effort, especially when dealing with repetitive tasks. This section explores how to use scripting languages like Bash and Python to automate the comparison process.

6.1 Using Bash Scripting for File Comparison

Bash scripting is a powerful way to automate tasks on Unix-like systems. You can use Bash to compare text files using the diff command and perform actions based on the comparison results.

Basic Bash Script:

Here’s a basic Bash script to compare two files and print a message indicating whether they are different:

#!/bin/bash

file1="file1.txt"
file2="file2.txt"

diff "$file1" "$file2" > /dev/null

if [ $? -ne 0 ]; then
  echo "The files are different."
else
  echo "The files are identical."
fi

Explanation:

• #!/bin/bash: Shebang line indicating the script should be executed with Bash.
• file1="file1.txt" and file2="file2.txt": Variables storing the names of the files to compare.
• diff "$file1" "$file2" > /dev/null: Compares the two files using the diff command. The output is redirected to /dev/null to suppress it.
• if [ $? -ne 0 ]; then: Checks the exit status of the diff command. An exit status of 0 indicates the files are identical, while a non-zero status indicates they are different.
• echo "The files are different." and echo "The files are identical.": Prints a message based on the comparison result.

Advanced Bash Script with Options:

You can add options to the diff command to customize the comparison. For example, to ignore whitespace and case differences:

#!/bin/bash

file1="file1.txt"
file2="file2.txt"

diff -iw "$file1" "$file2" > /dev/null

if [ $? -ne 0 ]; then
  echo "The files are different (ignoring whitespace and case)."
else
  echo "The files are identical (ignoring whitespace and case)."
fi

Comparing Directories:

To compare directories, you can use the -r option with the diff command:

#!/bin/bash

dir1="dir1"
dir2="dir2"

diff -r "$dir1" "$dir2"

if [ $? -ne 0 ]; then
  echo "The directories are different."
else
  echo "The directories are identical."
fi

6.2 Using Python for File Comparison

Python offers a more versatile and powerful way to automate file comparison. You can use the difflib module to compare text files and generate human-readable diffs.

Basic Python Script:

Here’s a basic Python script to compare two files and print the differences:

import difflib

def compare_files(file1, file2):
    with open(file1, 'r') as f1, open(file2, 'r') as f2:
        lines1 = f1.readlines()
        lines2 = f2.readlines()

    diff = difflib.Differ().compare(lines1, lines2)
    print('n'.join(diff))

file1 = "file1.txt"
file2 = "file2.txt"
compare_files(file1, file2)

Explanation:

• import difflib: Imports the difflib module, which provides tools for comparing sequences.
• def compare_files(file1, file2):: Defines a function to compare two files.
• with open(file1, 'r') as f1, open(file2, 'r') as f2:: Opens the two files in read mode.
• lines1 = f1.readlines() and lines2 = f2.readlines(): Reads the lines from each file into lists.
• diff = difflib.Differ().compare(lines1, lines2): Compares the two lists of lines using difflib.Differ().
• print('n'.join(diff)): Prints the differences to the console.

Generating a Unified Diff:

You can use the difflib.unified_diff function to generate a unified diff, similar to the diff -u command:

import difflib

def compare_files_unified(file1, file2):
    with open(file1, 'r') as f1, open(file2, 'r') as f2:
        lines1 = f1.readlines()
        lines2 = f2.readlines()

    diff = difflib.unified_diff(lines1, lines2, fromfile=file1, tofile=file2)
    print(''.join(diff))

file1 = "file1.txt"
file2 = "file2.txt"
compare_files_unified(file1, file2)

Ignoring Whitespace and Case Differences:

To ignore whitespace and case differences, you can preprocess the lines before comparing them:

import difflib

def compare_files_ignore_ws_case(file1, file2):
    def preprocess(line):
        return line.strip().lower()

    with open(file1, 'r') as f1, open(file2, 'r') as f2:
        lines1 = [preprocess(line) for line in f1.readlines()]
        lines2 = [preprocess(line) for line in f2.readlines()]

    diff = difflib.unified_diff(lines1, lines2, fromfile=file1, tofile=file2)
    print(''.join(diff))

file1 = "file1.txt"
file2 = "file2.txt"
compare_files_ignore_ws_case(file1, file2)

Comparing Directories:

To compare directories, you can use the os and filecmp